1. Field of the Invention
The present invention relates to a probe card or electrical contactor assembly and more particularly, to an integrated type probe card. The invention relates also to the fabrication of the integrated type probe card.
2. Description of the Related Art
Various probe cards or electrical contactor assemblies are seen in U.S. Pat. Nos. 4027935; 4754256; 5090118; 5475318; 6072190. These probe cards or electrical contactor assemblies are different in structural design, principle of action and method of fabrication, however they commonly have numerous drawbacks. Regular probe cards include cantilever type, for example, epoxy ring probe cards, and vertical type, for example, cobra probe cards. These two types require much labor to install probes (tungsten contact pins, lead contact pins, or steel contact pins) in the circuit board individually and to adjust the heights of the probes. Because of much human labor is used during fabrication, much fabrication time is required and unequal level status of the probes may affect test stability. Because each probe has a big part exposed to the outside without insulation, parasitic capacitance and induction may produce, resulting in attenuation of high frequency test signal and increase of crosstalk. If the surface of the circuit board under test is not in level, low deformability of probes cannot keep all probes in effective contact with the test points.
Further, there is a limitation to probe installation density by labor. The minimum pitch is about 50 μm for cantilever type, or about 100 μm for vertical type. High pin counts results in high manufacturing cost. This pin count limitation imparts a barrier to the development of electronic elements.
Further, in U.S. Pat. No. 2002/0080588A1, the spring members used for transmitting test signal from the probes to the circuit board are coiled metal wires. The gap between each two adjacent spring members is insufficient to eliminate crosstalk, and signal error may be produced. Crosstalk may cause an inaccurate test result.